BIOLOGY 2 Marks Questions

The full names and functions of the following hormones are :
(i) M.S.H. - Melanocyte Stimulating Hormone
Function : This hormone stimulates the spread of melanin granules in pigment cells found in the skin, deepening the skin colour. MSH is found in all vertebrates but is functionally active only in poikilothermal animals. This hormone is responsible for freckles and tans in humans.
(ii) A.C.T.H. : Adreno Corticotropic Hormone
Function : This hormone controls the growth of the adrenal cortex and regulates the hormones released from it.

The hormone released from the thyroid gland, thyroxine, is associated with a person's nature. In the appropriate amount, it maintains a person's normal behaviour. If the hormone level increases in the blood, metabolic activities accelerate, making the nervous system more sensitive. This makes a person irritable and jittery. Since the thyroid gland is associated with a person's nature, it is also known as the nature gland or behaviour gland.

Trophic Hormone : These are hormones that induce the growth, development, and maintenance of organs, especially endocrine glands, even though they're not of endocrine origin themselves.

S. No.	Diabetes Mellitus	Diabetes Insipidus
1.	It is due to deficiency of insulin.	It is due to definciency of ADH.
2.	The blood sugar becomes high and glucose appears in urine.	The blood glucose is normal and   glucose does not appear in urine.
3.	There is high blood cholesterol and ketone body formation.	There is no such phenomenon.

Pituitary gland hormones and their functions :
1. Thyroid Stimulating Hormone (TSH) : This hormone stimulates the thyroid gland, regulates the synthesis and release rate of thyroxine.
2. Adreno Cortico Trophic Hormone (ACTH) : It controls the secretion from the cortex of the adrenal gland.
3. Follicle-stimulating Hormone (FSH) : This hormone stimulates the follicles in the ovaries for development and maturation. It prompts the release of estrogens and the liberation of the ovum.
4. Luteotrophic Hormone (LTH) or Prolactin : This hormone, after ovulation, maintains the corpus luteum and keeps it producing progesterone. It collaborates with estrogen to regulate the development of mammary glands and stimulates milk secretion after childbirth.

Diabetic Coma occurs when there's an excess of insulin hormone, causing a decrease in glucose levels in the blood. As a result, brain cells do not receive sufficient glucose, leading the individual to lose consciousness.

The pineal gland is situated in the posterior part of the forebrain (upper part). It secretes a hormone called melatonin.
Functions of melatonin :
(1) It works antagonistically to the melanocytestimulating hormone (MSH) secreted from the adenohypophysis. It prompts the gathering of pigment granules in melanocytes, resulting in lightening of the skin colour.
(2) Melatonin inhibits the development and functionality of the reproductive organs in mammals.
(3) It regulates sexual behaviour based on variations in light exposure and functions similarly to the biological clock by controlling the biological rhythm.
(4) Removing this gland from humans and others causes puberty to occur quickly.
(5) Due to the unaffected response to light in blind infants, the deficiency of this hormone leads to early puberty.

Four important functions of hormones are as follows:
1. They regulate growth, development, maturation, and reproduction.
2. They also regulate various body metabolic processes, their dynamic variations, and energy expenditure.
3. They influence the function of the nervous system.
4. Most of an individual's personality and behaviour depend on endocrine glands.

(1) Growth-promoting : Several non-endocrine organs release many hormones that are known as growth promoting hormones. These hormones are necessary for the general growth, repair, and regeneration of tissues and organs.
(2) Gastrointestinal Tract : Various parts of the gastrointestinal tract contain endocrine cells that secrete four main peptide hormones, which are as follows :
(i) Gastrin : Acts on gastric glands to stimulate the secretion of H C l and pepsinogen.
(ii) Secretin : Acts on the exocrine pancreas, stimulating the secretion of water and bicarbonate ions.
(iii) Cholecystokinin : Acts successively on both the pancreas and gallbladder, promoting the secretion of pancreatic enzymes and bile.
(iv) Gastric Inhibitory Peptide (GIP) : Inhibits gastric secretion and its motility.
(3) Erythropoietin : Cells of the juxtaglomerular apparatus in the kidney produce erythropoietin, a hormone that stimulates the production of red blood cells (RBCs).
(4) Thyrocalcitonin : A protein hormone is secreted from the thyroid gland, known as thyrocalcitonin (TCT), which regulates the level of calcium in the blood.

The disease goiter is more common among people living in mountainous regions because there is a deficiency of iodine in the soil and water. The deficiency of iodine causes the goiter disease.

Diseases caused by the excessive secretion of the pituitary gland's growth hormone are :
(1) Gigantism : Excess of this hormone during childhood causes an abnormal increase in the body's size compared to normal.
(2) Acromegaly : If, after the normal growth in an adult, there is an increase in the amount of this hormone, the long bones of the body do not grow. During this time, there is an abnormal growth in the bones of the face, deforming the face. There is an increase in bone thickness. This is called acromegaly. It results in the creation of a hunch, known as kyphosis.

In the disease goiter, the thyroid gland enlarges, causing the neck to swell. This disease occurs due to a deficiency of iodine in the diet. People living in mountainous regions are more prone to this disease because there is a scarcity of iodine in the water.

The adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. These are commonly called as catecholamines. Adrenaline and noradrenaline are rapidly secreted in response to stress of any kind and during emergency situations and are called emergency hormones or hormones of Fight or Flight. These hormones increase alertness, pupilary dilation, piloerection (raising of hairs), sweating etc. Both the hormones increase the heart beat, the strength of heart contraction and the rate of respiration. Catecholamines also stimulate the breakdown of glycogen resulting in an increased concentration of glucose in blood. In addition, they also stimulate the breakdown of lipids and proteins.

Vasopressin or antidiuretic hormone's primary function is to increase reabsorption of water in the distal convoluted tubules and collecting ducts of the kidneys. Therefore, it's known as an antidiuretic hormone. Reduced secretion of this hormone leads to diluted urine and increased urine output, causing a condition called diabetes insipidus. As a result, dehydration occurs in the body, leading to excessive thirst.

Alpha cells produce glucagon hormone. Destruction of these cells would hinder the functions of glucagon, such as gluconeogenesis, glycogenolysis, and lipid breakdown in adipose tissue. Beta cells produce insulin hormone. Eliminating these cells would disrupt insulin functions, affecting glycolysis, lipogenesis, RNA synthesis, and control of glucose catabolism.